Loop antenna construction



' APYil129, 1947- I T. H. CLARK ETAL 2,419,539

LOOP ANTENNA CONSTRUCTION Filed March 5, I945 4 Sheets-Sheet 1 I INVENTORS TREVOR cMfi/r film/P J W061? 14 01/05 April 29, 1947- T. H. CLARK ET AL LOOP ANTENNA CONSTRUCTION Filed March 5, 1945 4 Sheets-Sheet 2 AITO April 1947- T. H. CLARK ET AL LOOP ANTENNA CONSTRUCTION Filed March 5, 1943 -4 Sheets-Sheet 3 April 29, T. CLARK 'Y A LOOP ANTENNA CONSTRUCTION I Filed March 5 1945 4 Sheets-Sheet 4 INVENTORS TREVOR h. CLARA Pfl/l/F J." M/Vflf/F 14 0005 A TTORAIE'Y Patented Apr. 29, 1947 UNITED STATES PATENT OFFICE LOOP ANTENNA CONSTRUCTION Trevor H. Clark, New York, and Philip J. Vander Woude, Riverdale, N. Y., assignors to Federal Telephone and Radio Corporation, Newark, N. J., a corporation of Delaware Application March 5, 1943, Serial No. 478,082

12 Claims.

This invention relates to improvements in loop antenna construction, and more particularly to a short-wave crossed loop wave collector adapted for installation on board ships, especially on top of masts.

An object of this invention is toprovide a novel improved antenna assembly including crossed loops, sense antenna, and counterpoise, which is especially adapted for use in connection with direction finding systems aboard ships.

Another object of this invention is to provide an antenna assembly of the type described which can readily be mounted upon the usual ship mast structures.

A further object of this invention is the provision of a novel hollow water-proof base member for receiving the ends of the loops in an antenna assembly which may include crossed loops, sense antenna and counterpoise.

An additional object of this invention is directed to providing a novel hollow supporting base for an antenna, assembly in which terminal blocks are mounted in and about the hollow base.

Still another object of our invention is the provision of a hollow base mounting for a loop antenna formed of flexible shielded cables.

With the foregoing and other objects in view which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of con- .struction hereinafter described and claimed.

The invention has been illustrated in its preferred embodiment in the accompanying drawings he in:

' Fig. 1 is a vertical view example of an antenna assembly which may be used with the present invention;

Fig. 2 is a top plan view of the general antenna assembly illustrated in Fig. 1;

Fig. 3 is an enlarged cross-sectional view of a novel base for the antenna assembly in accordance with the present invention;

Fig. 4 is a plan View of a terminal block used in the base shown in Fig. 3;

Fig. 5 is a cross-sectional view of the terminal block taken along the line 5-5 of Fi 4;

Fig. 6 is a cross sectional view of a cable holding device taken along the line 66 of Fig. 3.

The general antenna assembly will be readily apparent from a study of Figs. 1 and 2. Primarily, it includes a generally vertical supporting rod ID from the vertical mid-point of which extend four radial arms I2 spaced 90 relatively to one another and attached to the rod I 0 by means of a suitable connector I3. The bottom of the supporting rod I0 is held in a strengthening support It which, in turn, is mounted upon a generally hemispherical base member l6. The latter, in turn, may be attached to the top of a ship mast indicated at H. The four arms I2 may be interconnected by bracing bars 20 attached thereto by suitable clamping devices 22.

The crossed loop may be formed by two flexible shielded cables 24 and 26, the apices of which pass through a top mount I8 attached to the top of a supporting rod Ill, the ends of which are fastened within the base member I6 and the central portions of which are held by fastening devices 28 on the ends of the respective arms I2. top mount I8 may be fixed an insulating ring 29 which supports a metal cap 3%! from which projects a plurality of counterpoise rods 32. These rods are positioned at 90 relatively to one another. A sense antenna 34 extends vertically upwardly from an insulating disk 36 mounted on top of the cap 30. The particular manner of mounting the sense antenna, counterpoise rods, the connection between these two and the attachment of the crossed loop to the top mount I8 is all more fully described in the copending applicationof T. H. Clark, S. N. 78,081, filed March 5, 1943.

In Fig. 3 we have shown details of the novel hollow base member of the present invention, upon which the antenna system is mounted. This will consist of a generally hemispherical hollow casting I6 which will rest upon a suitable flange I3=8 on the top of the mast H. A watertight gasket I39 is interposed between the casting I6 and the flange I38 and rigid connection may be made through means such as bolts MI. The supporting rod Iil is held within the supporting base frame I4, the latter being attached to the top of the base casting IE as through bolts MD. A sealin gasket I42 is preferably interposed. The sloping sides of the casting I6 are formed with four spaced openings I44 to receive the ends of the loops 24 and 26. These loop ends must be rigidly attached to the base I Ii to give rigidity to the loops and the connection must be watertight. To eliect such an arrangement the openings I44 are provided on the outside with a circular internally threaded portion adapted to receive a collar I59 externally threaded at \both ends. One end of the collar I50 is threaded into i the openings I44 and presses against a grounding Above the which tightly grips the surface of the cable and is pressed against the cable and externally against the collar I50 by means of a compression nut I54 threaded over the other end of the collar. This arrangement holds the cables tightly with respect to the base I6, but leaves the extremities of the loops free-,of strain so that they may be readily connected to appropriate terminal blocks. Similar holding means are, of course, used to hold the lower ends of loop 26.

These terminal blocks are positioned around the bottom of the base 16 and are mounted in suitable openings therein. For the ends of the loops we have provided terminal blocks .155 which are attached to the base I6 by meanssuch a screws I58 and IE on the inner side of the terminal blocks I56, and held in place bythe nuts upon the screws I58 are clamps Hi2 which surround the shielded ends of the cable andrigidly hold them to the terminal block. Leads I extendgfrom each screw 1-58 to a common central .rod 166 passing from one side of the terminal -block-to-the other. A lead I68 on the outsideof :the terminal block connects the pin 136 to the shieldI-1Il of a flexible dual cable I12 extending down and: externally of the mast I1 to theradio equipment. The terminal blocks .Itfi .are also ,provided with a pair of through pins 114 to which are attached theendsof the loop conductors themselves. As willbecome clear from a study of Figs. 4 and 5 in connection with Fig. 3, be- .tween the pin 'l-l l and a second pair of pin I18 positionedirmnediately below themare attached resistors I16 for the .purpose of improving .the characteristics of the loop antenna, as more -clearly explained in thecopending application :of Daubaras,-S, N. 478,079, filed -March 5, 1943. The lowerpins-l 18 are. in turn, attached through leads I80 to the dual wires of the cable I12. The various pins I66, I14 and dare held in place in the terminal blocks by-enlarged fluted portions H57,

Thedual cables I12 forming the transmission line to theradio apparatus are held within the ..base I6 by means of rubber bushings I86 pressed about the'end thereof and mountedon one side in a cut-out section I84 of each terminal block andheld on the outside by a cover I99 which is attached about the openings in the base I6 as by bolts-I94. These covers at the same time serve 'to protect the exposed sides of the terminal blocks and in order to provide a water-tight con- .nection, suitable gaskets I94 may be interposed between each coverand the base.

The terminal block I56 serves for a dual cable -92 which may extend a dummy loop network (not shown) interconnecting the sense antenna :and counterpoisadownwardly through the hollow supporting rod 10, is similar in construction .to the terminal-blocks I55 but does not include the-clamps I62,.the pins I14 and the resistors I 16. Instead, an inner shield of the cable 92 is directly connected to the central pin I66 while the two wires from the dual cable are respectively directly connected to the lower pins 118. The pins 166 and I18 extend through'the terminal block 'I 56 and are connected with the dual cable I12 in a manner identical with that described in connection with the terminal blocks I56 and the dual cables I12.

In order to hold the dual cable 92 in place we have provided, as is more clearly indicated in Fig. 6, a clamp I91 attached to the underside of nthGEbaSB Ifi'by screws I98 inthe vicinity of the iopening for one end-of the cable '24, this clamp provided with at least three angularly spaced openings at .its side, a terminal block mounted ineach of said openings, a hollow supporting rod positionedonand communicating with said base member through the opening in the top thereof,.,a top mount, supported on the top of said supporting rod, Ffour arms positioned at right angles to one. another and extending radial- 1y outwardlyfrom substantially the vertical midpoint of saidsupporting rod, a loopantennacomprising two loops, each loop having its closedltop fixed in said top mount and its ends fixedinsaid loase member, one loop being-supported.by two oppositearms .and the other member beingsupportedby theother twooppositearms, whereby the two loopsare positioned at .90 relatively to one another,.a vertical, senseantenna supported from said topmount, acounterpoise attached to said top mount, said counterpoise comprising fourradially directed vrods extending-from said top mount at right angles to one another,..a transmission linev connected to said sense antenna and counterpoise, said transmission dine including ..a dual cable. extending from .said hollow-top. mount through-said hollow supportingrodintosaid base member, and means forconnecting the v.ends.of one loop ,toa first terminal block, the. ends. of-the other loop toa second terminal ,block,;and the lower ends ofsaid dualcableto-the thirdterminal block,

2. The'combination according .to claim .1, in which each of saidloops isformed of a .shielded insulated flexible cable, in combination with grounded clamping means on'said-first. and secend terminal blocks, respectively engaging .the shield on said-loops,

3. The combination according to .claim 1, .in combination with clamping -means attached to the inside of saidba-semember and-engagingsaid dual cable.

4. The combination according to claim .l,.in whicheach of-said terminalblocks is provided with terminal pins extending therethrough and the ends of the loops and the ends of the-dual cable areelectrically connected tothose terminal pins on the inside oi-the hollowbase member, in combination .with leadeout cables attached to the outer ends-of the pins, and covers attached to said base memberrespectively enclosing the outer ends of the pins of-each terminal block.

5. The combination according to .claim 1, in

-Which eaclrterminal blockis provided onthe-outside with aninwardly directed cut-out near .its lower end and with terminal .pins extending therethrough, and the ends of the loops and-the "ends of the dual :cable are electrically connected to those terminalrpinsronthe inside .of the hollow base member, in combination with.lead-out ca .bles respectively, attached to the outer-ends of the pins, lead-out cable fastening means positioned .in-eachof said cut-outs, ,and-covers attached to saidbase member respectively enclosing the outer ends of the pins of each terminal block and holding said cable fastening means in said cut-outs.

6. The combination according to claim 1, in which said base member is formed with openings in its shell to receive the ends of the loops, in combination with means in said openings grasping the loop passing therethrough and tightly attaching the same to the base member.

7. The combination according to claim 1, in which said base member is formed with openings in its shell to receive the ends of said loops, in combination with means in said openings forming a water-tight joint about the portions of the loop passing therethrough, and a water-tight covering attached on the outside of said shell about the outer side of each terminal block.

8. The combination according to claim 1, in combination with a strengthening support surrounding the lower end of said hollow supporting rod, and water-tight means for mounting said strengthening support on said base member.

9. A wave collector, including in combination, a hollow base member in the form of a generally hemispherical metal shell having at least three openiings in its side, a terminal block mounted in one of said openings, a vertical supporting rod mounted on said hollow base memher, a loop antenna attached to said supporting rod and having its lower end passing into said base member through the other openings therein, water-tight means firmly holding the loops in said two openings, a water-tight cover attached to said base member about the terminal block in the other opening, and means for electrically connecting the lower ends of the loop to said terminal block.

10. The combination according to claim 9, in which said loop is formed of a shielded flexible cable, in combination with grounded clamping means on said terminal block engaging the shields on the ends of the loop.

11. The combination according to claim 9, in which said terminal block is provided with terminal pins extending therethrough and the ends of said loops are connected to those pins on the inside of said base member, in combination with a lead-out cable positioned on the outside of said terminal block and within the terminal block cover attached to the outer ends of said pins.

12. Ihe combination according to claim 9, in which each terminal block is provided on the outside with an inwardly directed cut-out near its lower end and with terminal pins extending therethrough, and the ends of the loops and the ends of the dual cable are electrically connected to those terminal pins on the inside of the hollow base member, in combination with lead-out cables respectively attached to the outer ends of the pins, lead-out cables fastening means positioned in each of said cut-outs, and covers attached to said base member respectively enclosing the outer ends of the pins of each terminal block and holding said cable fastening means in said cut-outs.

TREVOR H. CLARK. PHILIP J. VANDER WOUDE. 

